This paper analyzes the process of perceptual recalibration (PR) in light of two cases of technologically-mediated cognition: sensory substitution and perceptual modification. We hold that PR is a very useful concept — perhaps necessary — for explaining the adaptive capacity that natural perceptive systems display as they respond to functional demands from the environment. We also survey critically related issues, such as the role of learning, training, and nervous system plasticity in the recalibrating process. Attention is given to the interaction between technology and cognition, and the case of epistemic prostheses is presented as an illustration. Finally, we address the following theoretical issues: (1) the dynamic character of spatial perception; (2) the role of functional demands in perception; (3) the nature and interaction of sensory modalities. We aim to show that these issues may be addressed empirically and conceptually — hence, the usefulness of sensory-substitution and perceptual-modification studies in the analysis of perception, technologically-mediated cognition, and cognition in general.